CN113252124B

CN113252124B - Flow rate measurement device, flow rate measurement method, and flow rate measurement program

Info

Publication number: CN113252124B
Application number: CN202110047077.4A
Authority: CN
Inventors: 铃村宜晓; 山本克行; 半田宪一; 中尾秀之
Original assignee: Omron Corp
Current assignee: Omron Corp
Priority date: 2020-02-10
Filing date: 2021-01-14
Publication date: 2024-11-12
Anticipated expiration: 2041-01-14

Abstract

The invention provides a flow rate measuring device, a flow rate measuring method and a flow rate measuring program, which aim at measuring object fluids with different thermal diffusivities, so that the measuring accuracy of the flow rate is further improved. The flow rate measuring device includes: the present invention provides a fluid flow control device including a flow rate detection unit for detecting a flow rate of a fluid to be measured flowing through a main flow passage, a characteristic value acquisition unit which includes a heating unit for heating the fluid to be measured and a temperature detection unit for detecting a temperature of the fluid to be measured and which acquires a characteristic value of the fluid to be measured, and a flow rate correction unit which corrects the flow rate of the fluid to be measured calculated based on a detection signal output from the flow rate detection unit by using the characteristic value of the fluid to be measured acquired by the characteristic value acquisition unit, wherein the heating unit and the temperature detection unit are arranged in parallel in a direction orthogonal to a flow direction of the fluid to be measured, and the characteristic value acquisition unit acquires the characteristic value by using a ratio of the temperatures of the fluid to be measured, the ratio of the temperatures of the fluid to be measured being a ratio of the temperatures of the fluid to be measured detected by the temperature detection unit before and after a temperature change of the heating unit.

Description

Flow rate measurement device, flow rate measurement method, and flow rate measurement program

Technical Field

The present invention relates to a flow rate measurement device, a flow rate measurement method, and a flow rate measurement program.

Background

Conventionally, a flow rate measuring device has been proposed which has a heating unit and a temperature detecting unit and measures the flow rate of a fluid to be measured. For example, there has also been proposed a flow rate measurement device including a physical property value detection unit for detecting a physical property value of a fluid to be measured in order to reduce a change in an output property due to a change in a physical property of the fluid to be measured (patent document 1). Specifically, the temperature difference between the micro heater and the thermopile is detected, to thereby obtain a thermal conductivity (thermal diffusion constant), and the flow rate measured by the sensor is corrected based on the thermal conductivity.

In addition, there has been proposed a flow rate measurement device that, for a fluid to be measured having different thermal diffusivities, prepares a substance detection micro heater and a thermopile arranged in parallel in a direction orthogonal to a flow direction of the fluid to be measured, and detects a difference in temperature between the fluid to be measured before and after changing the temperature of the micro heater in two steps in order to improve the measurement accuracy of the flow rate. In this technique, a characteristic value is obtained from a difference between temperatures of a fluid to be measured before and after changing the temperature of the micro heater in two steps, and the flow rate of the fluid to be measured is corrected by using the obtained characteristic value (patent document 2).

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2012-237776

Patent document 2: japanese patent application laid-open No. 2017-129470

Disclosure of Invention

Technical problem to be solved by the invention

However, when the types of the fluids to be measured are increased, it is difficult to sufficiently and accurately identify the physical properties of the fluids to be measured by using only the difference between the temperatures of the fluids to be measured detected by the thermopile before and after changing the temperature of the micro heater in two steps, and it is difficult to sufficiently improve the measurement accuracy of the flow rate for the fluids to be measured having different thermal diffusivities.

The present invention has been made in view of the above-described problems, and an object of the present invention is to further improve the flow rate measurement accuracy for a fluid to be measured having different thermal diffusivities.

Technical scheme for solving technical problems

The flow rate measurement device of the present invention comprises: a flow rate detection unit for detecting a flow rate of a fluid to be measured flowing through the main flow channel; a characteristic value acquisition unit that has a heating unit that heats a fluid to be measured and a temperature detection unit that detects the temperature of the fluid to be measured, and that acquires a characteristic value of the fluid to be measured; and a flow rate correction unit that corrects the flow rate of the fluid to be measured calculated based on the detection signal output from the flow rate detection unit, using the characteristic value of the fluid to be measured acquired by the characteristic value acquisition unit. The heating unit and the temperature detection unit are arranged in parallel in a direction orthogonal to a flow direction of the fluid to be measured, and the characteristic value acquisition unit acquires the characteristic value by using a ratio of temperatures of the fluid to be measured, the ratio being a ratio of temperatures of the fluid to be measured detected by the temperature detection unit before and after a temperature change of the heating unit.

When the characteristic value obtained from the ratio of the temperatures of the fluid to be measured detected by the temperature detection unit before and after the temperature change of the heating unit is used, correction corresponding to the thermal conductivity of the fluid to be measured and the thermal diffusivity that changes due to heat and viscosity can be performed. Therefore, the measurement accuracy of the flow rate can be improved for the fluid to be measured having different thermal diffusivities.

In the present invention, the characteristic value obtaining unit may obtain the characteristic value by using a ratio of a difference between temperatures of the fluid to be measured detected by the temperature detecting unit before and after the temperature change of the heating unit.

Here, among the fluids to be measured having different thermal diffusivities, there may be a fluid in which the difference between the temperatures of the fluids to be measured detected by the temperature detecting unit before and after the temperature change of the heating unit can be used to accurately reflect the physical characteristics, and a fluid in which the ratio between the temperatures of the fluids to be measured detected by the temperature detecting unit before and after the temperature change of the heating unit can be used to accurately reflect the physical characteristics. In the present invention, therefore, when the characteristic value obtaining unit obtains the characteristic value by using the ratio of the difference between the temperatures of the fluid to be measured detected by the temperature detecting unit before and after the temperature change of the heating unit, the characteristic value reflecting the physical characteristics of the fluid to be measured having different thermal diffusivities can be obtained with higher accuracy.

The characteristic value is obtained by multiplying a difference between temperatures and/or a ratio between temperatures of the fluid to be measured detected by the temperature detecting unit before and after the temperature change of the heating unit by a predetermined coefficient, and the flow rate correcting unit may correct the flow rate of the fluid to be measured by multiplying the characteristic value by a detection signal output from the flow rate detecting unit. Specifically, the above-described value may be used as the characteristic value.

The secondary flow path portion is provided with a characteristic value detection flow path having one end communicating with a first inflow port opening into the main flow path and the other end communicating with a first outflow port opening into the main flow path, thereby branching off from the main flow path, and the temperature detection portion is provided with a characteristic value acquisition portion. The flow rate detection unit may be disposed at a position different from the characteristic value detection flow path. By providing the auxiliary flow path portion, the flow rate measuring device can be provided irrespective of the size and flow rate of the main flow path. In addition, the temperature detection unit of the dust intrusion flow rate detection unit and the characteristic value acquisition unit can be suppressed.

The temperature detection unit and the flow rate detection unit of the characteristic value acquisition unit may be provided in a flow rate detection member which is detachably provided in a member constituting the main flow path or the sub flow path unit. In this way, it is possible to provide a fitting that can be attached to the main flow passage portion 2 of various flow rates and shapes, and the cost can be reduced.

The sub-flow path portion includes: the flow rate detection flow path and the characteristic value detection flow path may be formed by a first sub flow path portion having one end communicating with a first inlet opening into the main flow path and the other end communicating with a first outlet opening into the main flow path and flowing from the sub flow path portion, and a second sub flow path portion having one end communicating with a second inlet opening into the first sub flow path portion and the other end communicating with a second outlet opening into the first sub flow path portion and flowing from the first sub flow path portion, and the flow rate detection flow path and the characteristic value detection flow path may be further branched from the second sub flow path portion by one end communicating with a third inlet opening into the second sub flow path portion and the other end communicating with a third outlet opening into the second sub flow path portion. When the three-stage flow-dividing structure is adopted in this way, the amount of intrusion of dust into the flow rate detection unit and the temperature detection unit of the characteristic value acquisition unit can be further reduced.

The sub-flow path portion may further include a flow rate detection flow path in which the flow rate detection portion is disposed, and the flow rate detection flow path may have one end communicating with the first inlet and the other end communicating with the first outlet, and may branch the fluid to be measured flowing in from the first inlet to the characteristic value detection flow path and the flow rate detection flow path. The above-described structure may be employed as a specific split structure.

The sub-flow path portion may further include a flow rate detection flow path in which the flow rate detection portion is disposed, and the characteristic value detection flow path may be provided in the flow rate detection flow path so that a part of the fluid to be measured flowing in the flow rate detection flow path flows into the characteristic value detection flow path. The above-described structure may be employed as a specific split structure.

The secondary flow path portion may further include a flow rate detection flow path in which the flow rate detection portion is disposed, and one end of the flow rate detection flow path may be communicated with a fourth inlet opening into the main flow path, and the other end may be communicated with a fourth outlet opening into the main flow path. The above-described structure may be employed as a specific split structure.

The flow rate detection unit may be disposed in the main flow passage. In this way, the flow rate detection unit may be configured to take the fluid in the main flow path as a measurement target.

The heating portion may be disposed so that the longitudinal direction of the heating portion is along the flow direction of the fluid to be measured. In this way, the heating unit can heat the fluid to be measured over a wide range in the flow direction of the fluid to be measured.

The temperature detection unit may be disposed so that the longitudinal direction of the temperature detection unit is along the flow direction of the fluid to be measured. In this way, the temperature detection unit can detect the temperature in a wide range over the flow direction of the fluid to be measured.

The sub-flow path portion further includes a flow rate detection flow path in which the flow rate detection portion is disposed, and the flow rate detection flow path and the characteristic value detection flow path are formed by arranging the circuit board in parallel with the flow direction of the fluid to be measured in the sub-flow path portion or the flow path in which the fluid to be measured flows from the sub-flow path portion, and the temperature detection portions of the flow rate detection portion and the characteristic value acquisition portion may be provided on one surface and the opposite surface of the circuit board, respectively. The above-described structure may be employed as a specific split structure.

The contents of the technical means for solving the technical problems may be combined within a range not departing from the problems and technical ideas of the present invention. In addition, the content of the flow rate measurement device shown in the technical solution to the technical problem may be provided as a method or a program executed in a processor, a microcontroller, or the like.

ADVANTAGEOUS EFFECTS OF INVENTION

The measurement accuracy of the flow rate can be improved for the fluid to be measured having different thermal diffusivities.

Drawings

Fig. 1 is a perspective view showing a device configuration of a flow rate measurement device.

Fig. 2 is a longitudinal cross-sectional view of a flow measurement device.

Fig. 3 is a transverse cross-sectional view of a flow measurement device.

Fig. 4 is a perspective view showing an example of a sensor element used in the flow rate detection unit and the physical characteristic value acquisition unit.

Fig. 5 is a sectional view for explaining the construction of the sensor element.

Fig. 6 is a schematic plan view showing the configuration of the flow rate detection unit.

Fig. 7 is a plan view schematically showing the configuration of the physical characteristic value obtaining unit.

Fig. 8 is a block diagram showing a functional configuration of the flow rate measurement device.

Fig. 9 is a process flow chart showing an example of the flow rate measurement process.

Fig. 10 is a process flow chart showing an example of the characteristic value acquisition process.

Fig. 11 is a graph in which the vertical axis represents the sensor sensitivity ratio and the horizontal axis represents the thermal conductivity.

Fig. 12 is a graph in which the vertical axis represents the sensor sensitivity ratio and the horizontal axis represents Δt.

Fig. 13 is a diagram showing a flow rate measurement device.

Fig. 14 is a perspective view showing the sub-channel portion.

Fig. 15 is a diagram schematically showing the configuration of the physical characteristic value detection unit and the flow rate detection unit.

Fig. 16 is a schematic diagram for explaining the flow rate of the fluid to be measured which is branched into the physical characteristic value detection flow path and the flow rate detection flow path.

Fig. 17 is a plan view showing a modification of the physical characteristic value detection flow path and the flow rate detection flow path formed on the upper surface of the sub-flow path portion.

Fig. 18 is a schematic plan view of a configuration of a modification of the physical characteristic value detection unit.

Fig. 19 is a perspective view showing a flow rate measurement device.

Fig. 20 is a diagram showing another example of the flow rate measurement device.

Fig. 21 is a diagram showing another example of the flow rate measurement device.

Fig. 22 is a diagram showing an example of a multistage split type according to another modification.

Fig. 23 is a cross-sectional view for explaining another modification.

Detailed Description

Application example

Next, an application example of the present invention will be described with reference to the drawings. The present invention is applied to a flow rate measurement device 1 shown in the block diagram of fig. 8. In fig. 8, the flow rate measurement device 1 includes: a flow rate detection unit 11, a physical characteristic value detection unit 12, and a control unit 13. The flow rate detection unit 11 and the physical characteristic value detection unit 12 are constituted by a so-called thermal flow rate sensor 100 shown in fig. 4, which includes a heating unit formed by a micro heater 101 and a temperature detection unit formed by a thermopile 102. The flow rate detection unit 11 includes a first temperature detection unit 111 in the flow rate detection unit and a second temperature detection unit 112 in the flow rate detection unit. The physical characteristic value detection unit 12 includes a first temperature detection unit 121 in the physical characteristic value detection unit, a second temperature detection unit 122 in the physical characteristic value detection unit, and a heating unit 123 in the physical characteristic value detection unit.

The flow rate detection unit 11 outputs a value indicating the flow rate to the control unit 13. The physical characteristic value detection unit 12 outputs the temperature detection signal output from the first temperature detection unit 121 in the physical characteristic value detection unit and the second temperature detection unit 122 in the physical characteristic value detection unit to the flow rate calculation unit 133. More specifically, the temperature of the heating unit 123 in the physical characteristic value detection unit is changed in two steps by the control of the control unit 13, and the first temperature detection unit 121 in the physical characteristic value detection unit and the second temperature detection unit 122 in the physical characteristic value detection unit calculate the output values before and after the temperature change of the heating unit 123 in the physical characteristic value detection unit, and output the output values to the control unit 13.

The control unit 13 further includes: a correction processing unit 131, a characteristic value calculation unit 132, and a flow rate calculation unit 133. The flow rate calculation unit 133 calculates the flow rate of the fluid to be measured based on the detection value of the flow rate detection unit 11. The characteristic value calculation unit 132 calculates a characteristic value based on the detection value of the physical characteristic value detection unit 12. Specifically, the characteristic value calculating unit 132 multiplies the temperature of the micro heater 101, which is the heating unit 123 in the physical characteristic value detecting unit 12, by a predetermined coefficient before and after the change, and calculates the characteristic value by multiplying the ratio of the temperatures of the fluid to be measured detected by the thermopiles 102, which are the first temperature detecting unit 121 in the physical characteristic value detecting unit and the second temperature detecting unit 122 in the physical characteristic value detecting unit. The correction processing unit 131 corrects the flow rate calculated by the flow rate calculation unit 133 using the characteristic value. Thus, by using only the difference between the temperatures of the fluid to be measured detected by the thermopile before and after the two-stage change in the temperature of the micro-heater, the characteristic value of the fluid to be measured is obtained, and even when it is difficult to sufficiently accurately identify the physical characteristics of the fluid to be measured, the accuracy of the flow measurement of the fluid to be measured having different thermal diffusivities can be sufficiently improved.

Examples (example)

Next, a flow rate measurement device according to an embodiment of the present invention will be described with reference to the drawings. The following embodiments are examples of the flow rate measuring device, and the flow rate measuring device of the present invention is not limited to the following configuration.

Structure of device

Fig. 1 is a perspective view showing the device configuration of the flow rate measurement device according to the present embodiment. Fig. 2 is a longitudinal cross-sectional view of a flow measurement device. Fig. 3 is a transverse cross-sectional view of a flow measurement device. The flow rate measuring device is incorporated in, for example, a gas meter, a combustion apparatus, an internal combustion engine of an automobile, or a fuel cell, and measures the amount of gas passing through a flow path. The dashed arrows in fig. 1 illustrate the flow direction of the fluid. As shown in fig. 1 to 3, in the present embodiment, a flow rate measurement device 1 is provided inside a main flow channel portion 2. The flow rate measurement device 1 further includes: a flow rate detection unit 11, a physical characteristic value detection unit (also referred to as a "temperature detection unit") 12, and a control unit 13. The flow rate detection unit 11 and the physical characteristic value detection unit 12 are so-called thermal flow rate sensors including a heating unit formed of a micro heater and a temperature detection unit formed of a thermopile.

Fig. 4 is a perspective view showing an example of a sensor element used in the flow rate detection unit and the physical characteristic value acquisition unit. Fig. 5 is a cross-sectional view for explaining the structure of the sensor element. The sensor element 100 includes a micro heater (heating unit) 101 and thermopiles (temperature detecting units) 102 provided on both sides with the micro heater 101 interposed therebetween. Insulating films are formed on the upper and lower surfaces of the element and are provided on the silicon substrate. A cavity (void) is provided in the silicon substrate below the microheater 101 and thermopile 102. The micro heater 101 is, for example, a resistor formed of polysilicon. Fig. 5 schematically shows a temperature distribution in the case where the micro heater 101 generates heat by an oval shape of a broken line. The thicker the broken line, the higher the temperature. In the case where there is no air flow, as shown in the upper half (1) of fig. 5, the temperature distribution on both sides of the micro heater 101 is substantially the same. On the other hand, in the case where, for example, air flows in the direction indicated by the dotted arrow in the lower half (2) of fig. 5, the temperature of the leeward side of the micro heater 101 is higher than the temperature of the windward side because the surrounding air moves. The sensor element outputs a value indicating the flow rate by using the deviation of the heater heat distribution.

The control unit 13 in fig. 1 is formed by an arithmetic device such as a microcontroller, and calculates a flow rate based on the output of the flow rate detection unit 11, calculates a predetermined characteristic value based on the output of the physical characteristic value detection unit 12, or corrects the flow rate using the characteristic value.

Flow rate detection unit and physical characteristic value acquisition unit

Fig. 6 is a schematic plan view showing the configuration of the flow rate detection unit 11 shown in fig. 1, and fig. 7 is a schematic plan view showing the configuration of the physical characteristic value detection unit 12 shown in fig. 1.

As shown in fig. 6, the flow rate detection unit 11 includes: a first thermopile (first temperature detecting portion in the flow rate detecting portion) 111 and a second thermopile (second temperature detecting portion in the flow rate detecting portion) 112 that detect the temperature of the fluid to be measured, and a micro heater 113 that heats the fluid to be measured. The micro heater 113 is disposed in parallel with the first temperature detection unit 111 in the flow rate detection unit and the second temperature detection unit 112 in the flow rate detection unit 11 along the flow direction P of the fluid to be measured. The micro heater 113, the first temperature detection unit 111 in the flow rate detection unit, and the second temperature detection unit 112 in the flow rate detection unit are each substantially rectangular in shape in plan view, and the longitudinal direction of each is orthogonal to the flow direction P of the fluid to be measured.

The first temperature detection unit 111 in the flow rate detection unit and the second temperature detection unit 112 in the flow rate detection unit are disposed on the upstream side of the micro heater 113, and the first temperature detection unit 111 in the flow rate detection unit and the second temperature detection unit 112 in the flow rate detection unit are disposed on the downstream side thereof, so as to detect the temperature at the symmetrical position across the micro heater 113.

In the flow rate measurement device 1, the physical characteristic value detection unit 12 and the flow rate detection unit 11 are disposed so that the arrangement angles with respect to the flow direction of the fluid to be measured are different by 90 ° using sensors having substantially the same configuration. In this way, since the sensor having the same structure can be used as the physical characteristic value detection unit 12 or the flow rate detection unit 11, the manufacturing cost of the flow rate measurement device 1 can be reduced.

On the other hand, as shown in fig. 7, the physical characteristic value detection unit 12 includes: a first thermopile (first temperature detecting portion in the physical property value detecting portion) 121 and a second thermopile (second temperature detecting portion in the physical property value detecting portion) 122 that detect the temperature of the fluid to be measured, and a micro heater (heating portion in the physical property value detecting portion) 123 that heats the fluid to be measured. The physical characteristic value detection unit internal heating unit 123, the physical characteristic value detection unit internal first temperature detection unit 121, and the physical characteristic value detection unit internal second temperature detection unit 122 are arranged in parallel in the physical characteristic value detection unit 12 in a direction orthogonal to the flow direction Q of the fluid to be measured. The physical characteristic value detection section internal heating section 123, the physical characteristic value detection section internal first temperature detection section 121, and the physical characteristic value detection section internal second temperature detection section 122 are each substantially rectangular in shape in plan view, and each long side direction thereof is along the flow direction Q of the fluid to be measured. The first temperature detection unit 121 and the second temperature detection unit 122 are disposed symmetrically about the heating unit 123 in the physical characteristic value detection unit, and detect temperatures at symmetrical positions on both sides of the heating unit 123 in the physical characteristic value detection unit.

Here, since the temperature distribution is biased to the downstream side due to the flow of the fluid to be measured, the change in the temperature distribution in the direction orthogonal to the flow direction is smaller than the change in the temperature distribution in the flow direction of the fluid to be measured. Therefore, by arranging the first temperature detection unit 121 in the physical characteristic value detection unit, the heating unit 123 in the physical characteristic value detection unit, and the second temperature detection unit 122 in the physical characteristic value detection unit in the direction orthogonal to the flow direction of the fluid to be measured in this order, it is possible to reduce the variation in the output characteristics of the first temperature detection unit 121 in the physical characteristic value detection unit and the second temperature detection unit 122 in the physical characteristic value detection unit due to the variation in the temperature distribution. Therefore, the influence of the flow of the fluid to be measured on the change in the temperature distribution is reduced, and the detection accuracy of the physical characteristic value detection unit 12 can be improved.

Further, since the longitudinal direction of the in-physical-property-value-detecting-unit heating unit 123 is arranged along the flow direction of the fluid to be measured, the in-physical-property-value-detecting-unit heating unit 123 can heat the fluid to be measured over a wide range in the flow direction of the fluid to be measured. Therefore, even when the temperature distribution is biased to the downstream side due to the flow of the fluid to be measured, the variation in the output characteristics of the first temperature detecting portion 121 in the physical characteristic value detecting portion and the second temperature detecting portion 122 in the physical characteristic value detecting portion can be reduced. Therefore, the influence of the flow of the fluid to be measured on the change in the temperature distribution is reduced, and the detection accuracy of the physical characteristic value detection unit 12 can be improved.

Further, since the first temperature detection unit 121 in the physical characteristic value detection unit and the second temperature detection unit 122 in the physical characteristic value detection unit are arranged along the flow direction of the fluid to be measured, the first temperature detection unit 121 in the physical characteristic value detection unit and the second temperature detection unit 122 in the physical characteristic value detection unit can detect the temperature over a wide range in the flow direction of the fluid to be measured. Therefore, even when the temperature distribution is biased to the downstream side due to the flow of the fluid to be measured, the variation in the output characteristics of the first temperature detecting portion 121 in the physical characteristic value detecting portion and the second temperature detecting portion 122 in the physical characteristic value detecting portion can be reduced. Therefore, the influence of the flow of the fluid to be measured on the change in the temperature distribution is reduced, and the detection accuracy of the physical characteristic value detection unit 12 can be improved.

Functional structure

Fig. 8 is a block diagram showing a functional configuration of the flow rate measurement device. The flow rate measurement device 1 includes: a flow rate detection unit 11, a physical characteristic value detection unit 12, and a control unit 13. The flow rate detection unit 11 includes a first temperature detection unit 111 in the flow rate detection unit and a second temperature detection unit 112 in the flow rate detection unit. The physical characteristic value detection unit 12 includes: a first temperature detection unit 121 in the physical characteristic value detection unit, a second temperature detection unit 122 in the physical characteristic value detection unit, and a heating unit 123 in the physical characteristic value detection unit.

The flow rate detection unit 11 detects a value indicating the flow rate of the fluid to be measured based on temperature detection signals output from the first temperature detection unit 111 in the flow rate detection unit and the second temperature detection unit 112 in the flow rate detection unit. Specifically, the flow rate detection unit 11 calculates a difference between the temperature detection signal output from the first temperature detection unit 111 in the flow rate detection unit and the temperature detection signal output from the second temperature detection unit 112 in the flow rate detection unit, and obtains a value indicating the flow rate of the fluid to be measured based on the difference. Then, the flow rate detection unit 11 outputs a value indicating the flow rate to the control unit 13.

The physical characteristic value detection unit 12 outputs the temperature detection signal output from the first temperature detection unit 121 in the physical characteristic value detection unit and the second temperature detection unit 122 in the physical characteristic value detection unit to the flow rate calculation unit 133. Specifically, the physical characteristic value detection unit 12 obtains an average value of temperature detection signals output from the first temperature detection unit 121 in the physical characteristic value detection unit and the second temperature detection unit 122 in the physical characteristic value detection unit. The physical characteristic value detection unit internal heating unit 123 changes the temperature, for example, according to the control of the control unit 13. Thus, the first temperature detection unit 121 in the physical characteristic value detection unit and the second temperature detection unit 122 in the physical characteristic value detection unit can obtain the output values before and after the temperature change of the heating unit 123 in the physical characteristic value detection unit. The physical characteristic value detection unit 12 outputs the obtained output value to the control unit 13.

The control unit 13 further includes: a correction processing unit 131, a characteristic value calculation unit 132, and a flow rate calculation unit 133. The flow rate calculation unit 133 calculates the flow rate of the fluid to be measured based on the detection value of the flow rate detection unit 11. The characteristic value calculation unit 132 calculates a characteristic value based on the detection value of the physical characteristic value detection unit 12. Specifically, the characteristic value calculating unit 132 changes the temperature of the micro heater of the physical characteristic value detecting unit 12, multiplies the ratio of the temperature of the fluid to be measured detected by the thermopile before and after the change by a predetermined coefficient, and calculates the characteristic value. The correction processing unit 131 corrects the flow rate calculated by the flow rate calculation unit 133 using the characteristic value. The physical characteristic value detection unit 12 and the characteristic value calculation unit 132 are collectively referred to as a characteristic value acquisition unit.

< Flow measurement Process >)

Fig. 9 is a process flow chart showing an example of the flow rate measurement process. As shown in fig. 9, the flow rate detection unit 11 outputs temperature detection signals from the first temperature detection unit in the flow rate detection unit and the second temperature detection unit 112 in the flow rate detection unit, and the flow rate calculation unit 133 calculates the flow rate of the fluid to be measured based on the two temperature detection signals (fig. 9: s 1).

Specifically, the flow rate detection unit 11 outputs a temperature detection signal output from the first temperature detection unit 111 in the flow rate detection unit and a temperature detection signal output from the second temperature detection unit 112 in the flow rate detection unit. The flow rate calculation unit 133 calculates a difference between the two temperature detection signals, and calculates a value indicating the flow rate of the fluid to be measured based on the difference.

The method of calculating the flow rate of the fluid to be measured based on the temperature detection signals output from the first temperature detection unit 111 in the flow rate detection unit and the second temperature detection unit 112 in the flow rate detection unit may be a known method. The flow rate detection unit 11 outputs the calculated flow rate of the fluid to be measured to the control unit 13.

The physical characteristic value detection unit 12 also executes characteristic value acquisition processing (S2). The characteristic value acquisition process will be described in detail with reference to fig. 10.

Fig. 10 is a process flow chart showing an example of the characteristic value acquisition process. The characteristic value calculation unit 132 of the control unit 13 causes the in-physical characteristic value detection unit heating unit 123 of the physical characteristic value detection unit 12 to heat at a first temperature (fig. 10: s 11). Thereafter, the first temperature detection unit 121 in the physical characteristic value detection unit and the second temperature detection unit 122 in the physical characteristic value detection unit 12 detect the first temperature (S12). This step may be performed, for example, under the control of the control unit 13. The speed of heat propagating in the fluid to be measured depends on the physical property values such as thermal conductivity, thermal diffusivity, specific heat, and the like. Further, the thermal conductivity can be obtained by detecting the temperature difference between the heating section 123 in the physical characteristic value detection section and the first temperature detection section 121 in the physical characteristic value detection section and the second temperature detection section 122 in the physical characteristic value detection section. For example, the thermal conductivity decreases as the temperature difference between the physical characteristic value detection portion internal heating portion 123 and the first temperature detection portion 121 and the physical characteristic value detection portion internal second temperature detection portion 122 increases. By utilizing the above-described properties, in this step, the temperature of the fluid to be measured is detected by the first temperature detection unit 121 in the physical property value detection unit and the second temperature detection unit 122 in the physical property value detection unit, which are arranged in the direction orthogonal to the flow direction of the fluid to be measured.

Next, the characteristic value calculation unit 132 of the control unit 13 causes the in-physical characteristic value detection unit heating unit 123 of the physical characteristic value detection unit 12 to heat at the second temperature (S13). Thereafter, the first temperature detection unit 121 in the physical characteristic value detection unit and the second temperature detection unit 122 in the physical characteristic value detection unit 12 detect the second temperature (S14). This step may be performed, for example, under the control of the control unit 13. In this way, values indicating temperatures detected by the first temperature detecting unit 121 in the physical characteristic value detecting unit and the second temperature detecting unit 122 in the physical characteristic value detecting unit before and after the temperature change of the heating unit 123 in the physical characteristic value detecting unit are obtained.

The characteristic value calculation unit 132 calculates a characteristic value using the detected temperature (S15). In this step, the sensor sensitivity ratio is obtained. The sensor sensitivity ratio is a ratio of a sensor output value when a predetermined gas is flowing to a sensor output value when a reference gas is flowing, and is a characteristic value indicating thermal diffusivity. The sensor sensitivity ratio α is obtained by the following formula (1).

α＝β×rT ···(1)

Beta is a predetermined coefficient. Further, rT is a ratio of the detected values output from the first temperature detecting unit 121 in the physical characteristic value detecting unit and the second temperature detecting unit 122 in the physical characteristic value detecting unit before and after the temperature change of the heating unit 123 in the physical characteristic value detecting unit.

Thereafter, the processing returns to the processing of fig. 9, and the control unit 13 corrects the flow rate of the fluid to be measured calculated by the flow rate calculating unit by using the characteristic value (fig. 9: s 3). Specifically, the control unit 13 calculates the corrected flow rate by the following expression (2).

Corrected output = output of flow calculation section ×α·· (2)

In the present embodiment, the thermal diffusivity of the fluid to be measured can be detected in more detail by using the ratio (rT) of the temperatures detected by the thermopile before and after the temperature change of the micro heater. Here, the flow rate output from the thermal flow sensor has a correlation with the thermal diffusivity. Therefore, according to the flow rate correction processing of the present embodiment, correction can be performed appropriately for all the gases. That is, the measurement accuracy of the flow rate can be improved for the fluid to be measured having different thermal diffusivities.

Fig. 11 is a graph in which the vertical axis represents the sensor sensitivity ratio and the horizontal axis represents the thermal conductivity. Here, as shown in fig. 11, for example, when there are a plurality of gas groups having different physical characteristic values other than the thermal conductivity, such as mixed gases having different components, it is not possible to determine which sensor sensitivity ratio to use for correction by simply obtaining the thermal conductivity as the physical characteristic value. That is, in the method of correcting the heating temperature by a set of micro-heaters and the detected temperature of the thermopile, correction is performed based on two or more kinds of reference gases belonging to a predetermined gas group, but correction cannot be performed appropriately for a plurality of gas groups. Further, by using the difference Δt between the detected values output from the first temperature detecting unit 121 in the physical characteristic value detecting unit and the second temperature detecting unit 122 in the physical characteristic value detecting unit before and after the temperature change of the heating unit 123 in the physical characteristic value detecting unit, it is possible to calculate an appropriate characteristic value for the fluid to be measured, for which it is difficult to calculate the characteristic value sufficiently and with good accuracy.

Fig. 12 (a) is a graph in which the vertical axis represents the sensor sensitivity ratio and the horizontal axis represents Δt. For a gas in which the sensor sensitivity ratio is not approximately in line with the thermal conductivity as shown in fig. 11, the sensor sensitivity ratio may be approximately in line with Δt. Therefore, in the present embodiment, correction can be performed for a gas group whose thermal diffusivity is unknown. Fig. 12 (b) is a diagram showing the relationship among the average value, Δt, and rT of the outputs of the first temperature detecting unit 121 in the physical characteristic detecting unit and the second temperature detecting unit 122 in the physical characteristic detecting unit before and after the temperature change of the heating unit 123 in the physical characteristic detecting unit.

In the present embodiment, the characteristic value is calculated using the ratio (rT) of the temperatures detected by the thermopile before and after the temperature of the micro heater is changed. In addition, in the present embodiment, the characteristic value may be calculated using the difference (Δt) between the temperatures detected by the thermopile before and after the temperature of the micro heater is changed. The sensor sensitivity ratio α in this case can be obtained by the following equation (3).

α＝γ×rT+ε×ΔT ···(3)

Here, γ and ε are predetermined coefficients.

Thus, the characteristic value can be calculated using both the ratio (rT) of the temperatures detected by the thermopile before and after the temperature change of the micro-heater and the difference (DeltaT) of the temperatures detected by the thermopile before and after the temperature change of the micro-heater, which have a correlation with the thermal diffusivity, and the characteristic value can be calculated with higher accuracy. In the present embodiment, when the correlation between the thermal diffusivity of the fluid to be measured and the difference (Δt) between the temperatures detected by the thermopile before and after the temperature change of the micro heater is extremely high, the sensor sensitivity ratio α may be defined by the expression of Δt alone (a value obtained by multiplying Δt by a predetermined coefficient).

Modification example

In the above embodiment, the flow sensor of the flow rate measurement device 1 has been shown in which the fluid in the main flow path portion 2 is the object of measurement, but the present invention is not limited to the above example. For example, the flow sensor of the flow rate measurement device 1 may be configured to measure the fluid in the sub-flow path branched from the main flow path portion 2.

Fig. 13 (a) is an exploded perspective view showing the flow rate measurement device 1 according to the present embodiment, and fig. 13 (b) is a perspective view showing the flow rate measurement device 1 shown in fig. 13 (a). As shown in fig. 13 (a) and 13 (b), the flow rate measurement device 1 according to the modification includes: a main channel portion 2, a sub channel portion 3, a seal 4, a circuit board 5, and a lid 6.

The main flow path portion 2 is a tubular member penetrating in the longitudinal direction. An inflow port (first inflow port) 34 is formed on the upstream side and an outflow port (first outflow port) 35 is formed on the downstream side of the inner peripheral surface of the main channel portion 2 with respect to the flow direction O of the fluid to be measured.

In the present embodiment, the axial length of the main channel portion 2 is about 50mm, the diameter of the inner peripheral surface (inner diameter of the main channel portion 2) is about 20mm, and the outer diameter of the main channel portion 2 is about 24mm.

The sub-channel portion 3 is provided above the main channel portion 2, and has a sub-channel formed in the inside and on the upper surface thereof. One end of the sub flow path portion 3 communicates with the inflow port 34A, and the other end communicates with the outflow port 35A. In the flow rate measurement device 1, the sub-channel portion 3 is constituted by an inflow channel 34, a physical characteristic value detection channel 32, a flow rate detection channel 33, and an outflow channel 35.

The inflow channel 34 is a channel for flowing the fluid to be measured flowing through the main channel portion 2, and is branched into the physical characteristic value detection channel 32 and the flow rate detection channel 33. The inflow channel 34 is formed to penetrate the sub-channel portion 3 in a direction perpendicular to the main channel portion 2, and has one end communicating with the inflow port 34A and the other end opening on the upper surface of the main channel portion 2, and communicates with the physical characteristic value detection channel 32 and the flow rate detection channel 33. This makes it possible to divert a part of the fluid to be measured flowing through the main flow channel portion 2 to the physical characteristic value detection flow channel 32 and the flow rate detection flow channel 33 via the inflow flow channel 34.

The physical property value detection flow path 32 is a flow path having a longitudinal section of substantially コ and formed on the upper surface of the sub-flow path portion 3 and extending in a direction parallel to the main flow path portion 2. The physical property value detection portion 12 for detecting the physical property value of the fluid to be measured is disposed at a portion of the physical property value detection flow path 32 extending in the longitudinal direction (the direction parallel to the main flow path portion 2). One end of the physical property value detection flow path 32 communicates with the inflow port 34A via the inflow flow path 34, and the other end communicates with the outflow port 35A via the outflow flow path 35.

The flow rate detection flow path 33 is a flow path having a longitudinal cross section of substantially コ and formed on the upper surface of the sub-flow path portion 3 and extending in a direction parallel to the main flow path portion 2. A flow rate detection unit 11 for detecting the flow rate of the fluid to be measured is disposed at a portion extending in the longitudinal direction (direction parallel to the main flow path portion 2) of the flow rate detection flow path 33. One end of the flow rate detection flow path 33 communicates with the inflow port 34A via the inflow flow path 34, and the other end communicates with the outflow port 35A via the outflow flow path 35.

In the drawings, for convenience of explanation, the physical characteristic value detection unit 12 and the flow rate detection unit 11 are illustrated as being separated from the circuit board 5, but the physical characteristic value detection unit 12 and the flow rate detection unit 11 are disposed in the physical characteristic value detection flow path 32 or the flow rate detection flow path 33 in a state of being actually mounted on the circuit board 5.

The outflow channel 35 is a channel for flowing the fluid to be measured, which has passed through the physical characteristic value detection channel 32 and the flow rate detection channel 33, to the main channel portion 2. The outflow channel 35 is formed to penetrate the sub-channel portion 3 in a direction perpendicular to the main channel portion 2, and has one end communicating with the outflow port 35A and the other end opening on the upper surface of the main channel portion 2, and communicating with the physical characteristic value detection channel 32 and the flow rate detection channel 33. This allows the fluid to be measured, which has passed through the physical characteristic value detection flow path 32 and the flow rate detection flow path 33, to flow out to the main flow path portion 2 via the outflow flow path 35.

By thus branching the fluid to be measured flowing in from the same inlet 34A to the physical property value detection flow path 32 and the flow rate detection flow path 33, the physical property value detection unit 12 and the flow rate detection unit 11 can detect the physical property value or the flow rate based on the fluid to be measured having the same conditions such as temperature and concentration. Therefore, the measurement accuracy of the flow rate measurement device 1 can be improved.

In the flow rate measurement device 1, the sealing material 4 is inserted into the sub-channel portion 3, the circuit board 5 is disposed, and the circuit board 5 is fixed to the sub-channel portion 3 by the cover 6, thereby ensuring the air tightness of the inside of the sub-channel portion 3.

Fig. 14 is a perspective view showing the sub-channel 3 shown in fig. 13 (a). As shown in fig. 14, one end of the substantially コ -shaped physical characteristic value detection flow path 32 communicates with the inflow flow path 34, and the other end communicates with the outflow flow path 35. Similarly, one end of the flow rate detection flow path 33, which is substantially コ -shaped, communicates with the inflow flow path 34, and the other end communicates with the outflow flow path 35.

The physical characteristic value detection flow path 32 and the flow rate detection flow path 33 are also connected to each other at both ends, and the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 form a rectangular flow path on the upper surface of the sub-flow path portion 3.

In the flow rate measurement device 1, the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 are square in shape when viewed from a direction perpendicular to the upper surface of the sub-flow path portion 3, and are formed at positions symmetrical with respect to a straight line connecting the inflow flow path 34 and the outflow flow path 35.

In the present embodiment, the length of one side of each of the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 is about 4mm.

In the present embodiment, the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 are square in shape, but the present invention is not limited thereto. The shapes of the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 can be determined according to the shapes of the physical characteristic value detection unit 12 and the flow rate detection unit 11 to be arranged, as long as the physical characteristic value detection unit 12 and the flow rate detection unit 11 can be arranged.

Therefore, for example, when the physical characteristic value detection unit 12 is smaller in size than the physical characteristic value detection flow path 32, the width of the physical characteristic value detection flow path 32 may be matched with the width of the physical characteristic value detection flow path 32. In this case, the portion of the physical property value detection flow path 32 extending in the longitudinal direction is formed in a straight line shape. The same applies to the flow rate detection flow path 33.

Fig. 15 (a) is a schematic plan view showing the configuration of the physical characteristic value detection unit 12 shown in fig. 13, and fig. 15 (b) is a schematic plan view showing the configuration of the flow rate detection unit 11 shown in fig. 13. In the flow rate measurement device 1 shown in fig. 15, the widths of the flow paths extending in the longitudinal direction of the flow rate detection flow path 32 and the physical characteristic value detection flow path 33 are different from each other, and the width of the flow path in which the physical characteristic value detection unit 12 is disposed in the physical characteristic value detection flow path 32 is smaller than the width of the flow path in which the flow rate detection unit 11 is disposed in the flow rate detection flow path 33. In this way, in the flow rate measurement device 1, the flow rates of the fluid to be measured that are branched into the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 are individually controlled.

Fig. 16 is a schematic diagram for explaining the flow rate of the fluid to be measured which is branched into the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 shown in fig. 13. As shown in fig. 16, in the present embodiment, the widths of the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 are set so that the fluid to be measured at the flow rate P is branched to the physical characteristic value detection flow path 32 and the fluid to be measured at the flow rate Q is branched to the flow rate detection flow path 33.

The values of the flow rate P and the flow rate Q vary with the flow rate of the fluid to be measured flowing through the main flow path portion 2, but in a normal usage mode, the widths of the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 are set so that the flow rate P is a value within the detection range of the physical characteristic value detection portion 12 and the flow rate Q is a value within the detection range of the flow rate detection portion 11, respectively.

In the present embodiment, the width of the physical characteristic value detection flow path 32 is about 0.4mm, and the width of the flow rate detection flow path 33 is about 0.8mm.

In this way, in the flow rate measuring device 1, the flow rates of the fluid to be measured that is branched into the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 can be individually controlled by adjusting the respective widths. Accordingly, the flow rate of the fluid to be measured flowing through the physical property value detection flow path 32 can be controlled in accordance with the detection range of the physical property value detection unit 12, and the flow rate of the fluid to be measured flowing through the flow rate detection flow path 33 can be controlled in accordance with the detection range of the flow rate detection unit 11.

Therefore, the physical property value detecting unit 12 can detect the physical property value of the fluid to be measured at an optimum flow rate corresponding to the unique detection range, and therefore the detection accuracy of the physical property value detecting unit 12 can be improved.

Similarly, the flow rate detection unit 11 can detect the flow rate of the fluid to be measured at an optimal flow rate corresponding to the unique detection range, and therefore the detection accuracy of the flow rate detection unit 11 can be improved.

As shown in fig. 16, in the above-described modification example, the structure in which both the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 are formed in a substantially コ shape has been described, but the present invention is not limited to this. The physical characteristic value detection flow path 32 and the flow rate detection flow path 33 are not particularly limited as long as the flow rate of the fluid to be measured passing through the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 is set to a controllable width.

Fig. 17 (a) to 17 (d) are plan views showing modifications of the physical characteristic value detection flow path 32 and the flow rate detection flow path 33 formed on the upper surface of the sub-flow path portion 3 shown in fig. 16.

As shown in fig. 17 (a), for example, the physical characteristic value detection flow path 32 may be formed in a straight line shape, and the flow rate detection flow path 33 may be formed in a substantially コ shape.

As shown in fig. 17 (b) to 17 (d), the physical characteristic value detection flow path 32 may be formed so that the fluid to be measured flows into the physical characteristic value detection flow path 32 from a direction orthogonal to the direction in which the fluid to be measured flows into the flow rate detection flow path 33.

In this case, since the arrangement angle of the physical characteristic value detection unit 12 and the flow rate detection unit 11 can be made uniform, the process of actually mounting the physical characteristic value detection unit 12 and the flow rate detection unit 11 on the circuit board 5 in the manufacturing process of the flow rate measurement device 1 can be simplified.

As shown in fig. 15 (a), in the above-described modification example, the configuration has been described in which the physical property value detection unit 12 includes a physical property value detection unit internal heating unit 123 that heats the fluid to be measured, and a physical property value detection unit internal first temperature detection unit 121 and a physical property value detection unit internal second temperature detection unit 122 that detect the temperature of the fluid to be measured, and the physical property value detection unit internal first temperature detection unit 121 and the physical property value detection unit internal second temperature detection unit 122 are arranged symmetrically left and right across the physical property value detection unit internal heating unit 123, but the present invention is not limited to this.

Fig. 18 is a plan view schematically showing a configuration of a modification of the physical characteristic value detecting unit 12 shown in fig. 15 (a). As shown in fig. 18, the second temperature detection unit 122 in the physical characteristic value detection unit may be omitted, and the physical characteristic value detection unit 12a may be constituted by the heating unit 123 in the physical characteristic value detection unit and the first temperature detection unit 121 in the physical characteristic value detection unit.

In this way, the physical property value detection unit 12a can also be realized by arranging the heating unit in the physical property value detection unit and the first temperature detection unit in the physical property value detection unit in parallel in the direction orthogonal to the flow direction of the fluid to be measured.

Second modification example

Another modification of the flow rate measurement device according to the present invention will be described with reference to fig. 19. The components corresponding to the above embodiments are denoted by the corresponding reference numerals, and the description thereof is omitted. In the flow rate measuring device according to this modification, the flow rate detecting portion is disposed in the main flow path.

Fig. 19 (a) is a perspective view showing the flow rate measurement device 1a according to the present modification, fig. 19 (b) is a cross-sectional view showing the flow rate measurement device 1a shown in fig. 19 (a), and fig. 19 (c) is a plan view showing the sub-flow path portion 3a shown in fig. 19 (a).

As shown in fig. 19 (a) to 19 (c), in the flow rate measuring device 1a, an opening 37A is formed between the inlet 34A and the outlet 35A of the inner peripheral surface of the main flow path portion 2 a.

A cell-like flow rate detection flow path 37A in which the flow rate detection unit 11 is disposed is formed in the sub-flow path portion 3a, and the flow rate detection flow path 37A communicates with the opening 37A. Therefore, the fluid to be measured flowing through the main flow path portion 2a flows into the flow rate detection flow path 37A through the opening 37A, and the flow rate detection portion 11 detects the flow rate.

The flow rate of the fluid to be measured flowing from the main flow passage portion 2a into the flow rate detection flow passage 37A can be controlled by controlling and adjusting the size of the opening 37A.

The sub-channel portion 3a is constituted by an inflow channel 34, a physical property value detection channel 32, and an outflow channel 35, and a physical property value detection portion 12 for detecting a physical property value of the fluid to be measured is disposed in a channel extending in the longitudinal direction of the physical property value detection channel 32.

In this way, in the flow rate measurement device 1a, the physical characteristic value detection unit 12 is disposed in the sub-flow path unit 3a, and the flow rate detection unit 11 is disposed in the main flow path unit 2a. Therefore, in the flow rate measurement device 1a, the flow rate corresponding to the detection range of the physical characteristic value detection unit 12 can be controlled.

Therefore, according to the present embodiment, the change in the output characteristic due to the change in the physical characteristic of the fluid to be measured is reduced, and the flow rate measuring device 1a capable of measuring the flow rate of the fluid to be measured with high accuracy can be realized.

Third modification example

Another modification of the flow rate measurement device according to the present invention will be described with reference to fig. 20. The components corresponding to the embodiments are denoted by the corresponding reference numerals, and the description thereof is omitted.

The flow rate measurement device according to this modification differs from the above-described flow rate measurement device in that it has two independent sub-flow paths.

Fig. 20 (a) is a perspective view showing the flow rate measurement device 1b according to the present embodiment, and fig. 20 (b) is a plan view showing the sub-flow path portion 3 shown in fig. 20 (a).

As shown in fig. 20 (a) and 20 (b), in the flow rate measurement device 1b, the sub-flow path portion 3b has two sub-flow path portions formed in the inside and the upper surface thereof.

The first sub-flow path portion is constituted by an inflow flow path 34b, a physical property value detection flow path 32b, and an outflow flow path 35b, and a physical property value detection portion 12 for detecting a physical property value of the fluid to be measured is disposed in a flow path extending in the longitudinal direction of the physical property value detection flow path 32 b.

The second sub-flow path portion is constituted by an inflow flow path 34B, a flow rate detection flow path 33B, and an outflow flow path 35B, and a flow rate detection portion 11 for detecting the flow rate of the fluid to be measured is disposed in a flow path extending in the longitudinal direction of the flow rate detection flow path 33B.

In this way, in the flow rate measurement device 1b, the sub-channel portion 3b has two independent sub-channels, the physical characteristic value detection portion 12 is disposed in the first sub-channel portion, and the flow rate detection portion 11 is disposed in the second sub-channel portion. Therefore, according to the flow rate measuring device 1b, the flow rates corresponding to the detection ranges of the physical characteristic value detecting unit 12 and the flow rate detecting unit 11 can be individually controlled.

Therefore, according to the present embodiment, the change in the output characteristic due to the change in the physical characteristic of the fluid to be measured is reduced, and the flow rate measuring device 1b capable of measuring the flow rate of the fluid to be measured with high accuracy can be realized.

Fourth modification example

Another modification of the flow rate measurement device according to the present invention will be described with reference to fig. 21. The components corresponding to the embodiments are denoted by the corresponding reference numerals, and the description thereof is omitted.

The flow rate measurement device according to the present modification differs from the flow rate measurement device described above in that a flow path for detecting a physical characteristic value is formed in the flow path for detecting a flow rate.

Fig. 21 (a) is a perspective view showing a flow rate measurement device 1c according to the present embodiment, fig. 21 (b) is a perspective view showing a sub-flow path portion 3c shown in fig. 21 (a), and fig. 21 (c) is a plan view showing the sub-flow path portion 3c shown in fig. 21 (a).

As shown in fig. 21 (a) to 21 (c), in the flow rate measurement device 1c, the sub-flow path portion 3c is constituted by an inflow flow path 34, a physical characteristic value detection flow path 32c, a flow rate detection flow path 33c, and an outflow flow path 35.

In the sub-flow path portion 3c, a physical characteristic value detection flow path 32c is formed in the flow rate detection flow path 33c, and the flow rate detection portion 11 is disposed upstream and the physical characteristic value detection portion 12 is disposed downstream with respect to the flow direction of the fluid to be measured.

Here, the physical characteristic value detection flow path 32c is separated from the flow rate detection flow path 33c by a flow rate control member 40 for controlling the flow rate of the fluid to be measured, and the physical characteristic value detection unit 12 is disposed inside the flow rate control member 40.

The flow rate control member 40 is configured to control the flow rate of the fluid to be measured passing through the physical characteristic value detection flow path 32c, and includes a first side wall portion 40a and a second side wall portion 40 b. The first side wall portion 40a and the second side wall portion 40b are each substantially コ -shaped plate-like members, and are disposed at predetermined intervals in a state where the respective end portions are opposed to each other.

Therefore, by controlling the interval between the first side wall portion 40a and the second side wall portion 40b, the flow rate of the fluid to be measured passing through the physical characteristic value detection flow path 32c, which is the inside of the flow rate control member 40, can be adjusted.

In this way, in the flow rate measurement device 1c, since the sub-channel portion 3c has the flow rate control member 40 and the physical characteristic value detection channel 32c is provided inside the flow rate control member 40, the physical characteristic value detection channel 32c can be provided at an arbitrary position in the sub-channel portion 3c. Further, the flow rate control member 40 can easily control the flow rate of the fluid to be measured passing through the physical characteristic value detection flow path 32c.

In this way, even if the physical characteristic value detection flow path 32c is formed in the flow rate detection flow path 33c, the flow rates corresponding to the detection ranges of the physical characteristic value detection unit 12 and the flow rate detection unit 11 can be individually controlled.

Therefore, according to the present embodiment, the change in the output characteristic due to the change in the physical characteristic of the fluid to be measured is reduced, and the flow rate measuring device 1c capable of measuring the flow rate of the fluid to be measured with high accuracy can be realized.

[ Fifth modification ]

Fig. 22 (a) to 22 (c) are diagrams showing an example of a multistage split type according to another modification. Fig. 22 (c) shows the connection positions of the main flow path portion 2d and the flow rate measurement device 1 d. Fig. 22 (b) is an enlarged view of the position indicated by the rectangle indicated by the broken line in fig. 22 (c). Further, fig. 22 (a) is a sectional view A-A of the unit 1000 in fig. 22 (c). As shown in fig. 22 (b), in the present modification, a sub-channel portion 3d (having a smaller cross-sectional area) that is thinner than the main channel portion 2d is provided along the flow direction of the main channel portion 2. The sub-channel portion 3d is branched into a main channel 2e extending through the main channel portion 2d, and a sub-channel portion 3e connected substantially perpendicularly to the sub-channel portion 3d. As shown in fig. 22 (a), the sub-channel portion 3e is branched into a sub-channel portion 3f provided with the flow rate detection portion 11 and a sub-channel portion 3g provided with the physical characteristic value detection portion 12.

According to the modification having the above-described secondary flow path, the flow rate can be measured by the small-sized flow rate measuring device 1d irrespective of the flow rate of the primary flow path portion 2d (i.e., irrespective of the thickness (cross-sectional area) of the primary flow path portion 2 d). In addition, according to the modification having the above-described sub-flow path, intrusion of dust into the sensor chip can be suppressed, and measurement accuracy can be improved, and when the three-stage flow-dividing structure is adopted as in the modification shown in fig. 22, intrusion of dust can be further reduced.

As shown in fig. 22, for example, the unit 1000 may be formed by using a detachable fitting having the sub-channel portion 3f provided with the flow rate detection portion 11 and the sub-channel portion 3g provided with the physical characteristic value detection portion 12. In this way, it is possible to provide a fitting that can be attached to the main flow passage portion 2 of various flow rates and shapes, and the cost can be reduced.

Fig. 23 is a cross-sectional view for explaining another modification. In the example of fig. 23, the flow rate detection unit 11 and the physical characteristic value detection unit 12 are disposed on the front and rear surfaces of the circuit board, respectively. Further, a sub-channel is provided through the circuit board. The split structure shown in fig. 23 may be employed, not only in the form of providing a tubular sub-channel.

In the following, in order to make it possible to compare the structural main components of the present invention with those of the embodiments, reference numerals are added to describe the structural main components of the present invention.

< First invention >)

A flow rate measurement device (1), characterized by comprising:

a flow rate detection unit (11) for detecting the flow rate of a fluid to be measured flowing through a main flow channel;

A characteristic value acquisition unit that has a heating unit (123) for heating the fluid to be measured, and temperature detection units (121, 122) for detecting the temperature of the fluid to be measured, and that acquires a characteristic value of the fluid to be measured;

A flow rate correction unit (131) that corrects the flow rate of the fluid to be measured, which is calculated based on the detection signal output from the flow rate detection unit (11), using the characteristic value of the fluid to be measured acquired by the characteristic value acquisition unit;

The heating unit (123) and the temperature detection units (121, 122) are arranged in parallel in a direction orthogonal to the flow direction of the fluid to be measured,

The characteristic value obtaining unit obtains the characteristic value by using a ratio of temperatures of the fluid to be measured detected by the temperature detecting units (121, 122) before and after the temperature of the heating unit (123) is changed.

< Fourteenth invention >)

A flow rate measurement method for measuring a flow rate of a fluid to be measured by a flow rate measurement device (1), the flow rate measurement device (1) comprising:

a flow rate detection unit (11) that has a heating unit (113) for heating the fluid to be measured, which is disposed in parallel in the flow direction of the fluid to be measured, and temperature detection units (111, 112) for detecting the temperature of the fluid to be measured, and that detects the flow rate of the fluid to be measured flowing through the main flow path;

a characteristic value acquisition unit having a second heating unit (123) for heating the fluid to be measured, the second heating unit being arranged in parallel in a direction orthogonal to the flow of the fluid to be measured, and second temperature detection units (121, 123) for detecting the temperature of the fluid to be measured, the characteristic value acquisition unit being configured to acquire a characteristic value of the fluid to be measured;

the flow rate measurement method is characterized by comprising the following steps:

a flow rate detection step (S1) for detecting the flow rate of the fluid to be measured flowing through the main flow path by the flow rate detection unit (11);

a first temperature measurement step (S12) in which the temperature of the fluid to be measured is measured by the second temperature detection units (121, 123);

A temperature change step (S13) in which the temperature of the second heating unit (123) is changed;

A second temperature measurement step (S14) of measuring the temperature of the fluid to be measured by the second temperature detection units (121, 123) after the temperature change step (S13);

a characteristic value acquisition step (S15) for acquiring the characteristic value by using the ratio of the temperature of the fluid to be measured in the first temperature measurement step (S12) to the temperature of the fluid to be measured in the second temperature measurement step;

and a correction step (S3) for correcting the flow rate of the fluid to be measured detected in the flow rate detection step (S1) by multiplying the flow rate of the fluid to be measured by the characteristic value.

< Fifteenth invention >

A flow rate measurement program for causing a flow rate measurement device (1) to measure a flow rate of a fluid to be measured, the flow rate measurement device (1) comprising:

A flow rate detection unit (11) that has a heating unit (113) for heating a fluid to be measured, which is disposed in parallel in the flow direction of the fluid to be measured, and temperature detection units (111, 112) for detecting the temperature of the fluid to be measured, and that detects the flow rate of the fluid to be measured flowing through the main flow path;

A characteristic value acquisition unit that has a second heating unit (123) for heating the fluid to be measured, the second heating unit being arranged in parallel in a direction orthogonal to the flow of the fluid to be measured, and second temperature detection units (121, 123) for detecting the temperature of the fluid to be measured, and that acquires a characteristic value of the fluid to be measured;

the flow measurement procedure is characterized in that,

For executing the following steps in the information processing apparatus, that is to say,

A flow rate detection step (S1) for detecting the flow rate of the fluid to be measured flowing through the main flow channel by the flow rate detection unit (11);

A first temperature measurement step (S12) of measuring the temperature of the fluid to be measured by the second temperature detection units (121, 123);

A temperature change step (S13) of changing the temperature of the second heating unit (123);

A characteristic value acquisition step (S15) of acquiring the characteristic value by using the ratio of the temperature of the fluid to be measured in the first temperature measurement step (S12) to the temperature of the fluid to be measured in the second temperature measurement step;

Description of the reference numerals

1A flow measuring device; 2 a main flow path portion; 3 a secondary flow path portion; 5 a circuit substrate; 11 a flow rate detection unit; a first temperature detection unit in the 111 flow rate detection unit; 112 a second temperature detection section within the flow detection section; 113 micro-heaters; 12 physical characteristic value detection unit; 121a first temperature detection unit in the physical characteristic value detection unit; 122 a second temperature detection unit in the physical characteristic value detection unit; 123 physical property value detection unit internal heating unit; 13 a control part; a 131 correction processing unit; a 132 characteristic value calculation unit; 32 a physical characteristic value detection flow path; 33 flow rate detection flow paths; 34 an inflow channel; 100 sensor elements; 101 micro-heaters; 102 a thermopile; 1000 units.

Claims

1. A flow rate measurement device, comprising:

a flow rate detection unit for detecting a flow rate of a fluid to be measured flowing through the main flow channel;

A characteristic value acquisition unit for acquiring a characteristic value of a fluid to be measured, the characteristic value acquisition unit including a heating unit for heating the fluid to be measured and a temperature detection unit for detecting a temperature of the fluid to be measured;

a flow rate correction unit that corrects the flow rate of the fluid to be measured calculated based on the detection signal output from the flow rate detection unit, using the characteristic value of the fluid to be measured acquired by the characteristic value acquisition unit;

The heating unit and the temperature detecting unit are arranged in parallel in a direction orthogonal to a flow direction of the fluid to be measured,

The characteristic value obtaining unit obtains the characteristic value by using a ratio of temperatures of the fluid to be measured, the ratio being a ratio of temperatures of the fluid to be measured detected by the temperature detecting unit before and after the temperature of the heating unit is changed.

2. A flow measurement device according to claim 1, wherein,

The characteristic value obtaining unit obtains the characteristic value by using a ratio of a difference between temperatures of the fluid to be measured detected by the temperature detecting unit before and after the temperature change of the heating unit.

3. A flow measurement device according to claim 1, wherein,

The characteristic value is obtained by multiplying a difference and/or a ratio between temperatures of the fluid to be measured detected by the temperature detecting unit before and after the temperature change of the heating unit by a predetermined coefficient,

The flow rate correction unit corrects the flow rate of the fluid to be measured by multiplying the characteristic value by the detection signal output from the flow rate detection unit.

4. A flow measurement device according to claim 1, wherein,

And a sub-channel part having one end communicating with a first inlet opening into the main channel and the other end communicating with a first outlet opening into the main channel to branch from the main channel, and having a characteristic value detection channel of the temperature detection part provided with the characteristic value acquisition part,

The flow rate detection unit is disposed at a position different from the characteristic value detection flow path.

5. A flow measurement device according to claim 4, wherein,

The temperature detecting portion and the flow rate detecting portion of the characteristic value obtaining portion are provided in a flow rate detecting member that is detachably provided in a member constituting the main flow path or the sub flow path portion.

6. A flow measuring device according to claim 4 or 5, wherein,

The sub-flow path portion has:

a flow rate detection flow path in which the flow rate detection unit is disposed;

a first sub-channel portion having one end communicating with a first inlet opening into the main channel and the other end communicating with a first outlet opening into the main channel, thereby flowing from the sub-channel portion;

A second sub-channel portion having one end communicating with a second inlet opening in the first sub-channel portion and the other end communicating with a second outlet opening into the first sub-channel portion, thereby flowing from the first sub-channel portion;

the flow rate detection flow path and the characteristic value detection flow path are each formed by being further branched from the second sub-flow path portion with one end communicating with a third inlet opening in the second sub-flow path portion and with the other end communicating with a third outlet opening into the second sub-flow path portion.

7. A flow measuring device according to claim 4 or 5, wherein,

The sub-flow path portion further has a flow rate detection flow path in which the flow rate detection portion is disposed,

One end of the flow rate detection flow path is communicated with the first inflow port, and the other end is communicated with the first outflow port,

And branching the fluid to be measured flowing in from the first inlet to the characteristic value detection flow path and the flow rate detection flow path.

8. A flow measuring device according to claim 4 or 5, wherein,

The characteristic value detection flow path is provided in the flow rate detection flow path,

And causing a part of the fluid to be measured flowing in the flow rate detection flow path to flow into the characteristic value detection flow path.

9. A flow measuring device according to claim 4 or 5, wherein,

One end of the flow rate detection flow path is communicated with a fourth inflow port which is opened into the main flow path, and the other end is communicated with a fourth outflow port which is opened into the main flow path.

10. A flow measuring device according to any one of claims 1 to 5, wherein,

The flow rate detection unit is disposed in the main flow path.

11. A flow measuring device according to any one of claims 1 to 5, wherein,

The heating portion is disposed along a longitudinal direction of the fluid to be measured.

12. A flow measuring device according to any one of claims 1 to 5, wherein,

The temperature detection unit is disposed along the flow direction of the fluid to be measured in the longitudinal direction.

13. A flow measuring device according to claim 4 or 5, wherein,

The flow rate detection flow path and the characteristic value detection flow path are formed by arranging a circuit board on the flow path of the sub-flow path portion or the flow path flowing from the sub-flow path portion in parallel with the flow direction of the fluid to be measured,

The flow rate detection unit and the temperature detection unit of the characteristic value acquisition unit are provided on one surface and the opposite surface of the circuit board, respectively.

14. A flow rate measuring method for measuring a flow rate of a fluid to be measured by a flow rate measuring device, the flow rate measuring device comprising:

A flow rate detection unit that has a heating unit for heating a fluid to be measured, the heating unit being arranged in parallel in a flow direction of the fluid to be measured, and a temperature detection unit for detecting a temperature of the fluid to be measured, the flow rate detection unit being configured to detect a flow rate of the fluid to be measured flowing through a main flow path;

A characteristic value acquisition unit for acquiring a characteristic value of the fluid to be measured, the characteristic value acquisition unit including a second heating unit for heating the fluid to be measured, the second heating unit being disposed in parallel in a direction orthogonal to a flow direction of the fluid to be measured, and a second temperature detection unit for detecting a temperature of the fluid to be measured;

A flow rate detection step of detecting, by the flow rate detection unit, a flow rate of the fluid to be measured flowing through the main flow passage;

A first temperature measurement step of measuring a temperature of the fluid to be measured by the second temperature detection unit;

A temperature change step of changing the temperature of the second heating unit;

A second temperature measurement step of measuring the temperature of the fluid to be measured by the second temperature detection unit after the temperature change step;

a characteristic value obtaining step of obtaining the characteristic value by using a ratio of the temperature of the fluid to be measured in the first temperature measuring step to the temperature of the fluid to be measured in the second temperature measuring step;

And a correction step of correcting the flow rate of the fluid to be measured detected in the flow rate detection step by multiplying the flow rate of the fluid to be measured by the characteristic value.

15. A flow rate measurement program for causing a flow rate measurement device to measure a flow rate of a fluid to be measured, the flow rate measurement device comprising:

the flow measurement procedure is characterized in that,

In the information processing apparatus, steps are performed that,

a second temperature measurement step of measuring a temperature of the fluid to be measured by the second temperature detection unit after the temperature change step;

A characteristic value obtaining step of obtaining the characteristic value using a ratio of the temperature of the fluid to be measured in the first temperature measuring step to the temperature of the fluid to be measured in the second temperature measuring step;